on The Creative Penn:

Your book has been published, the publicity links have been made, and royalties are beginning to arrive as you breathe a sigh of relief.
Then realization hits – you need an idea for your next novel. Maybe because your previous book just flowed so easily, you took it for granted that an idea for your next book would be there when you were ready. But now there is just a blank page instead of a great rough draft.
So many authors seem to be prolific – authors like John Grisham, James Patterson, and Danielle Steel seem to produce new novels almost monthly.